Printing ink mainly consists of a dye, a resin which serves as a binding and thickening agent, and a solvent or a mixture of solvents. The printing-ink resins used are chiefly colophony derivatives. Colophony is a natural product, the supply and price of which are subject to fluctuations. It is therefore important that other sources of printing-ink resins be available.
The object of the present invention is the preparation of a resin that can be used as a printing-ink resin, and, more in particular, a resin that can be used in very rapidly drying rotogravure inks.
A resin of this type will have to meet the following requirements:
A. THE SOLUBILITY IN THE USUAL SOLVENTS, SUCH AS TOLUENE AND MIXTURES OF TOLUENE AND GASOLINE HAVING A BOILING RANGE OF 80.degree.-110.degree.C must be satisfactory. For some applications, even complete solubility in gasoline is desired;
B. A SOLUTION WITH A HIGH CONTENT MUST HAVE A REASONABLE VISCOSITY, E.G. 100-500 CP for a 50 % toluene solution;
C. THE MELTING POINT MUST BE REASONABLY HIGH, PREFERABLY 140.degree.C or more;
D. THE PIGMENT-WETTING MUST BE SATISFACTORY;
E. A RESIN SOLUTION MUST DRY RAPIDLY;
F. THE RESIN LAYER OR INK LAYER OBTAINED UPON DRYING MUST BE RUB-RESISTANT.
A resin that meets the above requirements may also be used in other fields, e.g. in lacquer and varnish, as a refining agent for paper and textiles, as a coating or as an admixture or diluent in other polymers.